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comparisons. The percent changes in rate-pressure product were compared between the dexmedetomidine groups and the placebo group using one-way analysis of variance and Dunnett's post hoc test. Descriptive statistics were used for demographic and ischemia data because of the small number of patients in each group. Data are reported as the mean plus/minus SD. P < 0.05 identified statistical significance. All statistical calculations were performed rising PC SAS 6.04 (SAS Institute, Cery, NC) software. The clinical and demographic data were similar for all groups). All 24 patients were men. The clinical course of the patient who was withdrawn from study was uneventful until his emergent return to surgery for revascularization. The induction doses of alfentanil, thiopental, and the intraoperative isoflurane requirements for the dexmedetomidine groups were not different from the placebo group Both heart rate and systolic blood pressure decreased in response to the 1-h dexmedetomidine infusion Compared with the placebo group, the decrease in heart rate was significant for the low-dose (P = 0.037) and high-dose (P = 0.004) groups and the decrease in systolic blood pressure was significant for the medium-dose (P = 0.01) and high-dose (P = 0.004) groups In the high-dose group, the heart rate decreased from 79 plus/minus 13 beats/min to 64 plus/min 15 beats/min (20% decrease), and the systolic blood pressure decreased from 168 plus/minus 27 mmHg to 133 plus/minus 27 mmHg (20% decrease). In the high-dose group, we observed an initial 2–11-mmHg increase in systolic blood pressure, followed by a decrease at 5 min after starting infusion. Changes in Page heart rate (top) and systolic blood pressure (bottom) values for each patient in response to the 1-h preinduction dexmedetomidine infusion. The first data point represents the value before preinduction infusion, and the second data point represents the value at the end of the 60-min infusion. *Significantly different (P < 0.05) from placebo. Heart rate and systolic blood pressure increased in all patients in response to intubation. On the average, the heart rates increased by 32%, 22%, 43%, and 21% for the placebo, low-, medium-, and high-dose groups, respectively (P = NS). The respective increases in the systolic blood pressure were 51%, 35%, 26%, and 31%(P = NS). During emergence from anesthesia, on the average, the heart rate values increased by 29%, 19%, 31%, and 0% above preoperative noninvasive baseline values and the systolic blood pressures increased by 27%, 31%, 9%, and 18% above preoperative noninvasive baseline values for the placebo, low-, medium-, and high-dose groups, respectively (P = NS). The rate-pressure product decreased in response to the 1-h preinduction dexmedetomidine infusion Compared to the placebo group, the decrease was significant for the medium-dose (P < 0.05) and high-dose (P < 0.05) groups. In response to intubation, the rate-pressure product of the dexmedetomidine groups were not different from placebo group. The rate-pressure product increased in response to emergence from anesthesia the high-dose group being significantly different from the placebo group (P < 0.01). Percent changes in the rate-pressure product (compared to the rate-pressure product immediately before the study drug infusion) in response to the 1-h preinduction study drug infusion (INF), intubation (INTUB), and emergence from anesthesia (EMERG). Data are presented as mean plus/minus SD. *Significantly different (P > 0.05) from placebo.Postoperatively, during dexmedetomidine infusion, the mean heart rates of the high-dose group were less compared to the placebo group (P = 0.036). None of the other mean heart rate or systolic blood pressure values of the dexmedetomidine groups differed significantly from those in the placebo group Mean Heart Rate and Systolic Blood Pressure (SBP) Values The amount of bradycardia was negligible in all groups Intraoperatively, the total amount of tachycardia was 0.56 min/monitored h in the high-dose group and 8.71 min/monitored h in the placebo group (P = NS; Postoperatively, during
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